Leafminer

Leafminers (Liriomyza spp.)

Credit: Biovision-Infonet

Mines cause by maggots, and a pupa of leafminer flies
(c) A.M. Varela, icipe

Leafmining flies make tiny punctures on the side of tomato leaves when feeding and laying eggs. These punctures may serve as entry point for disease causing organisms such as bacteria and fungi.

The most destructive stages are the immature stages (maggots). Maggots measure up to 3 mm in length. The maggots feed on leaf tissue inside the leaf leaving a wandering track in the form of irregular mines. Heavy mining of leaves may reduce photosynthesis affecting development of flowers and fruits. Heavy attack may cause leaf drop. This is particularly serious for tomato seedlings which may die due to defoliation. Defoliation of tomato plants may also expose fruits to sunburn and affect the market value. Leafminers attack a wide range of cultivated vegetables.

Damage by leafmining flies (Liriomyza spp.) on tomato leaf. Note maggot ready to pupate (yellow) and pupa (brown).
(c) A. M. Varela, icipe
What to do:
Conserve natural enemies. Parasitic wasps normally
control leafminers. However, the widespread
indiscriminate use of persistent broad-spectrum
insecticides, to control this and other pests, disrupt the
natural control, leading to leafminer outbreaks.

Rotate with non-host crops and plan the arrangement of fields so that old infested fields do not provide a reservoir of infestation for subsequent crops.

Destroy leafminer pupae in the soil. This can be done by ploughing and tilling, by solarisation, and, on heavy soils, by flood irrigation.

Monitor the crop by checking foliage for the presence of stipples caused by the adults while feeding and laying
eggs, and for mines and larvae. Trap adult flies with
yellow sticky or water traps.
If necessary spray with neem-based pesticides. For more information on Neem-based pesticides click here.

Leafminer (Liriomyza spp.) symptoms on Onions

(c) Courtesy EcoPort (http://www.ecoport.org): P. Ooi

Leafminers may cause damage to green onions. Damage is largely cosmetic, and mining on leaves may cause rejection of marketed onions, but generally does not affect plant growth. Damage in dry onions and garlic is of little concern unless populations become high to prematurely kill foliage.What to do:

  • Leafminers are usually controlled by natural enemies, especially parasitic wasps. They can become a problem in areas with a high use of pesticides that kill natural enemies. Leafminers have the ability to develop resistance to pesticides in a short time.

Tuta Absoluta

Tuta absoluta (tomato leaf miner)

Credit: Biovision-Infonet

Tomato leaf miner feeding
(c) Goldlocki, 2005
Tuta absoluta adult
(c) Marja van der Straten, NVWA Plant Protection Service, Bugwood.org

Tuta absoluta is a new insect pest of tomato plant in sub Saharan Africa. The moth pest originated from Peru and has spread to Europe, Africa and Asia. In Africa, T. absoluta was detected in Tunisia (2009), Ethiopia (2012), Senegal (2013), Sudan (2010) , Tanzania and Kenya (2014) and in Uganda (2015). Although tomato plant is the main host for T. absoluta, the pest also attacks other plants in the Solanacea family including potato, nightshade, eggplant, pepino, tobacco and solanaceous weeds such as Datura.

The life cycle of T. absoluta is completed within 30-35 days. T. absoluta can have 10-12 generations per year. Females can lay up  250-300 eggs on host plants. Eggs are small, cylindrical, creamy-white to yellow and approximately 0.35 mm long. Eggs hatch in 4-6 days after egg laying. The larva is cream-colored with a characteristic dark head. T. absoluta has four larval instars. Pupation may take place in the soil, on the leaf surface or within mines. The adults are small moths with 5-7 mm body length. The adults have thread-like antennae and forewings with grey scales and black spots.

The larvae feed between the leaf layers causing irregular mines. They eventually tunnel into the stems or burrow into the fruits, leaving black frass as it tunnels.

T. absoluta is a very challenging pest to control because of its fast reproductive rate (10 -12 generations per year), short life cycle, nocturnal adults, and concealed larval stage inside the plant parts. It can cause up to 100% loss of tomato fruits if left uncontrolled.

What to do:
Remove alternate host plants such as 
Datura stramonium, volunteer potato, eggplant or tomato plants.
Remove and destroy all infested plants and fruits
Practice crop rotation and intercropping
Mass trapping of leaf miner by using pheromone traps
Bio-pesticides such as Bacillus thuringiensis and neem
For more on neem click here
Bio-control agents, especially parasitoids
For more on parasitoids click here

Thrips

Thrips (Thrips tabaci, Frankliniella occidentalis, F. schultzeii and Ceratothripoides brunneus)

Thrips damage on tomato. Thrips are small (about 1 to 2 mm long)
(c) A.M. Varela, icipe
Thrips damage to flower buds on tomato
(c) A.M.Varela, icipe
Thrips damage to tomato leaflet
(c) A.M.Varela, icipe
Thrips damage to tomato
(c) A.A. Seif

Thrips may also be a problem in tomatoes in Kenya. Thrips are small (about 1 to 2 mm long). They usually feed on the lower surface of leaves puncturing them and suck the exuding sap. They also attack buds, flowers and fruits. Attacked leaves have a silvery sheen and show small black spots (thrips excrements). Under heavy infestation attacked buds, and flowers usually fall off. Attacked fruits show speckling and small necrotic patches on the surface affecting fruit quality. Fruits may become deformed.

Thrips feed on tomatoes at all stages, but their feeding on seedlings is particularly damaging. Heavy infestation can reduce stands of young seedlings in hot weather. Thrips of the genus Thrips and Frankliniella are vectors of viruses such as the Tomato Spotted Wilt Virus (the most economically important virus in tomato production) and the Tomato Chlorotic Spot Virus.

What to do:
Conserve natural enemies. Predatory mites
(eg. Amblyseius sp.), anthocorid bugs (e.g. Orius spp.),
and other predators such as ladybird beetles, lacewings and spiders, and the fungus Entomophthora are
important in natural control of thrips.
Monitor the crop regularly. Check plants daily in the
nursery, and crop borders in the field. Be particularly vigilant at flowering. Pay careful attention to flowers and
flower buds.
Destroy thrips pupae in the soil. This helps reducing
subsequent thrips populations. Plough and harrow
before transplanting to expose pupae in the soil from
previously infested crops to natural enemies and
desiccation. Soil solarisation and flood irrigation
(flooding previously infested fields prior to planting/transplanting) destroy a large proportion of thrips pupae
present in the soil.
If necessary spray biopesticides. Neem and some other plant extracts are reported to control thrips. Spinosad,
a bacterial derivative is effective in thrips control.
However, timing of biopesticide application is important. Thrips are difficult to control with insecticides due to
their secretive habits (eggs are laid in plant tissue, the
larvae and adult shelter in the flowers and larvae pupate
in the soil).
Spraying early in the morning or in the evening and
mixing the spray with a sugar solution (which attracts the thrips out of the flowers) are reported to increase
efficacy of sprays
For more on biopesticides click here

Tobacco Whitefly

Tobacco whitefly (Bemisia tabaci)

Credit: Biovision-Infonet

Whiteflies on chilli leaf. Adults are about 1mm long.
(c) B. Nyambo, A. A. Seif, icipe

Tobacco whitefly is a serious pest of tomatoes. Whiteflies attack tomatoes from seedling to mature stage. They suck sap from the leaves, and may weaken the plants. Feeding of whiteflies cause yellowing of infested leaves. Immature stages (nymphs) produce honeydew on which sooty mould grows. Heavy honeydew or mould coating reduces plant growth and fruit quality.

The main damage caused by whiteflies is indirect as vectors of virus diseases. Bemisia tabaci transmits several virus diseases in tomato. In particular it is an efficient vector of the Tomato Yellow Leaf Curl Virus (TYLCV), a major disease in Kenya.

Small numbers of whiteflies do not cause major direct plant damage. However, even small numbers of whiteflies may need to be controlled in areas where TYLCV is common.

What to do:
Time sowing and transplanting. If possible avoid the
season when whiteflies are more likely to occur.

Use cover crops (forage, peanut, weeds) and inert covers (silver, yellow, and white/black plastic mulches). They
have been shown to reduce whitefly damage in
tomatoes. Whiteflies are attracted by the colour of the
plastic mulch. The heat of the plastic kills the whiteflies.
However, this is effective as long as the plants are young and do not cover the mulch. The protection can last for 10 to 20 days after transplanting and about 30 days after direct seeding. Take care to avoid sunscald when using
plastic covers.

Prevent physical contact of the whiteflies with the plant;
this can prevent the transmission of viral diseases. Cover tomato seedling nurseries with nylon nets or use tunnels for 3 to 5 weeks to protect seedlings from whiteflies
infestation. These methods have been reported to
reduce the transmission of the Tomato Yellow Leaf Curl
Virus in several countries.

Conserve natural enemies. Whiteflies are mainly attacked by parasitic wasps and by predators such as phytoseiid mites, lacewings and ladybird beetles. For more information on Natural enemies click here

Check the crop regularly. Use yellow sticky traps to
monitor the presence of whitefly adults. Yellow traps are also an effective control method of whitefly at low infestations.

Remove weeds in advance of planting tomatoes, and
keep tomato fields weed-free. Weeds play an important
role in harbouring whiteflies between crop plantings.
They also often harbour whitefly-transmitted viruses.

If necessary spray neem extracts. Neem-based
insecticides are reported to substantially reduce egg
laying by B. tabaci, inhibit the growth and development
of nymphs, and significantly reduce the risk of TYLCV
transmission. For more on neem click here

Spraying with soap and water solutions reportedly
controls whiteflies. The amount of soap needed depends upon the soap type.

Plant barrier crops. Fenugreek and coriander are reported to repel whiteflies.

Root-knot nematodes

Root-knot nematodes (Meloidogyne spp.)

Credit: Biovision-Infonet

Root-knot nematodes are very destructive to tomatoes. Damage is most serious on light sandy soils in furrow-irrigated crops. The nematodes cause small lumps known as root knots or galls on the roots. Heavily infected roots are severely distorted and swollen. In time the roots rot. The affected plants are either stunted or have tendency to wilt or even die in hot weather. The affected plants, in most cases, just wilt with the foliage still green – without yellowing. The nematode problem is primarily due to improper crop rotation.

Root-knot nematodes (Meloidogyne incognita / M. javanica) Roots of severely attacked (left) and healthy plant (right). Affected plants are normally stunted and eventually wilt and die. The most characteristic symptom is formation of root galls (knots) and these can be seen with the naked eye. Affected roots rot.
(c) A. M. Varela, icipe
What to do:
Rotate with tomato, brassicas or cereals.
Do not locate seedbeds where susceptible vegetables (e.g. okra, sweet pepper, eggplant, Irish potato, carrot or cucurbits) have been previously grown.
Use tolerant or resistant tomato varieties (e.g. “Roma VNF”, “Shengena”,”Tengeru-97″, “Kentom”, “Caracas”, “Carmello”, “Diego”, “Piersol” and “Vegas”). Varieties with the “VFN” label exhibit some resistance – the “N” stands for Nematode-tolerant.
Use mixed cropping or grow marigolds (Tagetes spp.) or sunnhemp (Crotalaria juncea).
Maintain high levels of organic matter in the soil (manure and compost).
Amend the soil with neem. Mixing neem cake (residue of neem seed after expression of neem oil) increases the organic content of the soil and kills nematodes due to the naturally-occurring nematicidal compounds in neem.
More on neem click here

In Coffee

Root-knot nematodes (Meloidogyne spp.)

Root-knot nematode (Meloidogyne exigua) damage on coffee on the right. The trees are somehow stunted and yellowish.
(c) Jonathan D. Eisenback, Virginia Polytechnic Institute and State University, Bugwood.org
Root-knot nematode damage on coffee root system
(c) Roger Lopez-Chaves, Universidad de Costa Rica, Bugwood.org

Important nematodes attacking both Arabica and Robusta coffee are Meloidogyne arenaria, Meloidogyne decalineata and Meloidogyne incognita, causing root knots and galls. Other nematode species include Pratylenchus coffeae, Radopholus similis, Rotylenchus iperoiguensis and Rotylenchus pararobustus.

Field symptoms are typically of stunted, poorly growing plants with yellowing leaves. Infected root systems show characteristic knots or galls, the severity of which varies with the degree of nematode infection and species and variety of plant parasitized. Strategies of cultural control are less well developed and crop rotations are difficult to design because of the wide host range of Root-knot nematodes. Groundnuts or maize, which are both poor or non-hosts to M. incognita, have been evaluated for use in cropping systems designed to manage this nematode.What to do:

  • Ensure seedlings are nematode-free prior to transplanting
  • Incorporate neem extracts into the seed beds where nematode problem is known to occur

Aphids

Aphids (Aphis gossypii, Myzus persicae)

Credit: Biovision-Infonet

Aphids such as cotton aphid (Aphis gossypii) and the green peach aphid (Myzus persicae) suck plant sap, which can reduce plant growth; they also secrete honeydew, on which sooty moulds growth. Sooty mould on fruits reduces their market value. These aphids may also transmit virus diseases during feeding such as the cucumber mosaic virus. In Kenya, aphids are occasionally found on tomatoes, but they are not considered an important pest.

Green peach aphid (Myzus persicae) . Adult wingless females are 1.2-2.1 mm in body length and very variable in colour.
(c) Whitney Cranshaw, Colorado State University, Bugwood.org
What to do:
Conserve natural enemies. Aphids are usually kept under control by a wide range of natural enemies. For more
information on Natural enemies click here
In particular, avoid use of wide spectrum pesticides since they kill natural enemies.
Use reflective mulch. Reflective aluminium mulches
deter aphids from landing on plants. The effect is lost
once plants are large enough to cover the mulch.
Use biopesticides that are not harmful to natural enemies (e.g. neem, ashes, soapy water).  For more information
on Biopesticides click here
For more on Aphids click here

Cutworms General

Credit: Biovision-Infonet

Cutworms (Agrotis spp)

Cutworms are the caterpillars of certain moths. They are serious pests of tomato seedlings. They cut stems of newly transplanted or emerged plants at the base. Cutworm damage is more critical after thinning or transplanting.

Cutworms Agrotis spp on tomato. Note cut seedling. Early instars are about 7 to 12 mm long. Fully grown caterpillars are 35 to 50 mm long.
A. M. Varela, icipe
What to do:
Eliminate weeds early, at least 2 weeks before 
transplanting.
Plough and harrow the field prior to transplanting. This
exposes cutworms to natural enemies and desiccation
and helps destroy plant residue that could harbour
cutworms.

Make barriers to protect the transplanted seedlings.
Barriers can be made by wrapping paper, aluminium foil,
thin cardboard or similar materials around the base of
transplant stems. Toilet rolls are handy as cutworm
collars since they are readily available and will
biodegrade into the soil.

Dig near damaged seedlings and destroy cutworms.
Conserve natural enemies. Parasitic wasps and ants are
important in natural control of cutworms.

For more on cutworms click here

Cutworms in Maize

Cutworms cut maize seedlings at or a little below ground level, make small holes along the initial leaves, or remove sections from the leaf margins.

What to do:

  • Eliminate weeds early, at least 2 weeks before transplanting.
  • Plough and harrow the field prior to transplanting. This exposes cutworms to natural enemies and desiccation and helps destroy plant residue that could harbour cutworms.
  • Make barriers to protect the transplanted seedlings. Barriers can be made by wrapping paper, aluminium foil, thin cardboard or similar materials around the base of transplant stems. Toilet rolls are handy as cutworm collars since they are readily available and will biodegrade into the soil.
  • Dig near damaged seedlings and destroy cutworms.
  • Conserve natural enemies. Parasitic wasps and ants are important in natural control of cutworms.

CH 8. Camel Information Source Links

  • Dahlborn, K., Benlamlih, S., Zine, F.R., Guerouali, A., Hossaini, H.J. and Oukessou, M. (1992). Food deprivation and refeeding in the camel. The American Physiological Society. 262 (Regulatory Integrative Comp. Physiol. 31 :1000 – 1005.
  • Engelhardt, W., Haarmeyer, P. and Lechner-Doll, M. (2006). Feed intake, forestomach fluid volume, dilution rate and mean retention of fluid in the forestomach during water deprivation and rehydration in camels (Camelus sp.). Comparative Biochemistry and Physiology, Part A, 143:504 – 507.
  • Evans, J.O., Simpkin, S.P., Atkins, D.J. (eds) (1994). Camel Keeping in Kenya (The Camel Handbook). Range Management Handbook of Kenya Volume III, 8, Ministry of Agriculture, Livestock Development and Marketing, Range Management Division Nairobi 1994. 
  • Field, C.R. (1988). Characteristics and physiology of camels. In: S. P. Simpkin Camel Production, A series of lectures given by FARM-Africa at Nairobi University pp 23
  • Field, C.R., and Simpkin, S.P. (1985). The importance of camels to subsistence pastoralists in Kenya. IPAL Technical Report E7, UNESCO, Nairobi (Kenya)
  • http://www.fao.org
  • Gitao, G.C. (2006). Camel Husbandry: A Practical Guide to Camel Husbandry. Intermediate Communnications Ltd., Nairobi (Kenya).
  • Glucks, I.V. (2007). The prevalence of bacterial and protozoal intestinal pathogens in suckling camel calves in Northern Kenya, Freie Universitat Berlin, Mensch und Buch Verlag, Germany
  • Guliye, A.Y., Noor, I.M., Bebe, B.O., and Kosgey, I.S. (2007). The role of camels (Camelus dromedarius) in the traditional lifestyle of the Somali pastoralists in the arid and semi-arid areas of northern Kenya. Outlook on Agriculture, 36(1):29 – 34.
  • Heller, R., Lechner, M., Weyreter, H., Von Engelhardt, W. (1986). Forestomach fluid volume and retention of fluid and particles in the gastrointestinal tract of the camel (Camelus dromedarius). Journal of Veterinary Medicine, Series A 33, 396 – 399.
  • Hulsebusch, C.G., and Kaufmann, B.A., (2002). Camel breeds and breeding in northern Kenya: An account of local camel breeds of northern Kenya and camel breeding management of Turkana, Rendille, Gabbra and Somali pastoralists. Kenya Agricultural Research Institute (KARI) Nairobi-Kenya
  • KALRO, Manual in camel husbandry for service providers: http://www.kalro.org/
  • Kuria, S.G., (2004). Mineral nutrition on settlement (manyatta)-based milk camel herds among the Rendille community of northern Kenya. PhD Dissertation, University of Nairobi-Kenya
  • Kohler-Rollefson, I., Mundy, P. and Mathias, E. (2001). A field manual of camel diseases, Traditional and modern health care for the dromedary, ITDG Publishing, UK. ISBN-10: 185339503X
  • Lechner-Doll, M,, Rutagwenda, T., Schwartz, H.J., Schultka, W., Von Engelhardt, W. (1990). Seasonal changes of ingesta mean retention time and forestomach fluid volume in indigenous camels, cattle, sheep and goats grazing a thornbush savannah pasture in Kenya. Journal of Agricultural Science, 115:409 – 420.
  • Manefield, G.W., and Tinson, A.H., (1996). Camels A Compendium, IN: The TG Hungerford Vade Mecum Series for Domestic Animals, Series C, No 22, University of Sydney Post Graduate Foundation in Veterinary Science
  • Ndikumana, J., Stuth, J., Kamidi, R., Ossiya, S., Marambii, R., and Hamlett, P. (2000). Coping mechanisms and their efficacy in disaster-prone pastoral systems of the Greater Horn of Africa, ILRI Project Report, Nairobi, 124 pages.
  • Onono, J.O. et al. Challenges of camel production in Samburu District, Kenya. Journal of Camelid Science 3 (2010) 01-05.
  • Rutagwenga, T., Lechner-Doll, M., Scwartz, H. Z., Schultka, W., Von Engelhardt, W. (1990). Dietary preference and degradability of forage on a semi-arid thornbush savannah by indigenous ruminants, camels and donkeys. Animal Feed Science and Technology. 31, 179 – 192.
  • Schwartz, H.J., and Dioli, M. (1992). The one-humped camel in Eastern Africa: A pictorial guide to diseases, health care and management. Verlag Josef Margraf, Weikersheim (Germany). ISBN-10: 3823612182
  • Wernery, U., and Kaaden, O.R., (2002). Infectious Diseases in Camelids, Blackwell Science Berlin Vienna, Boston, Copenhagen, Edinburgh, London, Melbourne, Oxford, Tokyo 2nd Edition. ISBN 3826333047, 9783826333040
  • Wilson, R.T. (1989). The nutritional requirements of camel. Options Mediterraneennes – Serie Seminaires- n.O 2 – 1989: 171 – 179.
  • Wilson, R.T. (1995), Anatomy of the camel. In: J O Evans, S P Simpkin and D J Atkins (Eds.) Camel keeping in Kenya, Range Management Handbook of Kenya, Volume III, 8. pp. 6:8-6:12. Republic of Kenya,Ministry of Agriculture, Livestock Development and Marketing, Nairobi, Kenya.
  • Wilson, R.T. (1998). Camels. The Tropical Agriculturist Series, Macmillan Education Ltd (London) and CTA (Wageningen).
  • Yagil, R. (1985). The Desert Camel: Comparative Physiological Adaptation. Comparative Animal Nutrition, Vol. 5, Basel (Switzerland). ISBN: 978-3-8055-4065-0

CH 7. Camel Diseases Symptoms and Treatment

Trypanosomiasis

Not all trypanosomiasis parasites are transmitted by the tsetse fly. Trypanosoma evansi (thryps) is a very serious camel parasite mostly spread by biting flies. The parasite replicates in camels, horses, dogs, cattle, water-buffaloes and elephants. Equines and dogs are susceptible and usually die from the infection. Cattle sheep, goats and antelopes often become infected and act as asymptomatic carriers.

Symptoms: Thryps affects camels of all ages, with a higher incidence of disease in sub-adult camels shortly after weaning. Many environmental and host factors have impact on the course of the disease such as other infections, nutritional status, age, pregnancy, previous exposure, etc. If the several of the following symptoms are present in an animal, it is wise to get it tested and if positive, get it treated:

  • Visible weight loss, the hump starts drooping
  • Lack of appetite
  • Swellings (oedema) may appear on feet, brisket, underbelly and eyelids
  • Fluctuating body temperature with initial peaks of fever up to 41degC
  • Shivering
  • Mild diarrhea
  • Different smell of urine
  • Abortion

Diagnosis: The best tool for diagnosing thryps in the field is a battery-operated mini centrifuge for testing the camels blood. Such equipment should be operated by a vet or other trained animal health officers. 

Treatment: The best drug to combat thryps currently is Triquin. In order to calculate the correct dose the approximate weight of the sick camel must be known (see Bodyweight estimation). 
NOTE: Triquin is only meant to treat camels. Do not use on any other animal. Examples are known of goats being injected with this drug and dying immediately.
Other important camel diseases are:

Skin Diseases of Camels

  • Camel Pox
  • Sarcoptic Mange
  • Ringworm
  • Ticks
  • Flies
  • Bacteriological skin infections
  • Abscesses of the skin and external lymph nodes

Gastrointestinal helminthes of camels

  • Roundworms
  • Tapeworms
  • Liver Flukes

List of Laboratories for analysis of camel diseases

  • Analabs, Kenya Limited; P. O. Box Nairobi
  • Kenya Agricultural Research Institute (KARI), Marsabit; P.O Box 147-60500; Tel.+254 069 210 2040; Fax +254 069 210 2220
  • KARI, Trypanosomosis Research Centre; P.O. Box 362 – 00902 Kikuyu; Tel. +254 66 32960/4; Fax +254 66 32397; E-mail trccd@kari-trc.org, ketri2@bidii.com
  • KALRO, National Veterinary Research Centre; P. O. Box 32 – 00902 Kikuyu; Tel. +254 066 32106/2, 32000, 32703; Fax +254 066 32450; E-mail vrckari@yahoo.com

CH 6. Camel Herd Management

Management differ among different camel keeping societies, but all try to keep a predominantly female herd. The camels are usually kept in thorny enclosures over night, where they can be inspected, milked and generally looked after and kept safe from predators. 

Where camels are kept as part of a mixed herd, the watering intervals follow the other animals, but where camels are kept separately, watering intervals may be increased gradually up to 2 weeks, enabling camel herds look for browse from a very large distance from water sources.

Well fed camels, which are kept away from areas with biting flies and tsetse flies rarely become sick, but droughts, excessive rains, lack of browse and other debilitating factors can lead to diseases in camels.